Many products, such as granular and liquid materials, are shipped and stored in large bulk bags adapted to hold as much as a ton or more of material. The use of bags for this purpose has become popular recently because the bags can be shipped from the manufacturer to the material shipper in a generally collapsed and flat condition and, if properly designed, when empty can be returned by the user to the shipper in the same generally collapsed and flat condition for reuse.
A bag used in the above manner has to fulfill several practical requirements. It is of primary importance that the construction of the bag be such as to sustain relatively heavy loads. At the same time, it is essential that the bag be adapted to be folded or collapsed when empty to a compact and preferably flat form. Frequently, because of the nature and quantity of material shipped in such bags, the bags should also be designed so that they can be easily filled and emptied of their contents. It is also desired that such bags be designed so that, when filled, they are free standing and capable of being stacked vertically one upon another. Furthermore, depending upon the type of material being shipped, some bags are also required to be moisture-proof, water resistant, impervious and/or hygenic in which case a liner is provided having a similar configuration to the bags. A particularly satisfactory bag and loose liner which can be inserted into and removed from the bag is disclosed in U.S. Pat. No. 4,596,040.
Another flexible bag with a liner permanently secured therein by stitching along the side edges of the bag is disclosed in U.S. Pat. No. 4,597,102.
When a liner is used in connection with such large bags to contain particulate or granular material and the bag is formed with an opening or a spout at one or both ends for discharging the contents, a common problem is the tendency for the material when discharged to draw the liner out of the bag. Frequently, this discharge produces sufficient force to tear a liner stitched to the bag along its side edges so that it must collapse with the bag.
Objects, features and advantages of this invention are to provide a large bag with a liner which obviates the aforementioned problems; wherein the liner may be either readily and easily removable and replaceable or permanently attached to the bag, and is of economical manufacture and assembly.